A solution scan of societal options to reduce transmission and spread of respiratory viruses: SARS-CoV-2 as a case study

Societal biosecurity – measures built into everyday society to minimize risks from pests and diseases – is an important aspect of managing epidemics and pandemics. We aimed to identify societal options for reducing the transmission and spread of respiratory viruses. We used SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) as a case study to meet the immediate need to manage the COVID-19 pandemic and eventually transition to more normal societal conditions, and to catalog options for managing similar pandemics in the future. We used a ‘solution scanning’ approach. We read the literature; consulted psychology, public health, medical, and solution scanning experts; crowd-sourced options using social media; and collated comments on a preprint. Here, we present a list of 519 possible measures to reduce SARS-CoV-2 transmission and spread. We provide a long list of options for policymakers and businesses to consider when designing biosecurity plans to combat SARS-CoV-2 and similar pathogens in the future. We also developed an online application to help with this process. We encourage testing of actions, documentation of outcomes, revisions to the current list, and the addition of further options.</p

Black Hole Spin via Continuum Fitting and the Role of Spin in Powering Transient Jets

The spins of ten stellar black holes have been measured using the continuum-fitting method. These black holes are located in two distinct classes of X-ray binary systems, one that is persistently X-ray bright and another that is transient. Both the persistent and transient black holes remain for long periods in a state where their spectra are dominated by a thermal accretion disk component. The spin of a black hole of known mass and distance can be measured by fitting this thermal continuum spectrum to the thin-disk model of Novikov and Thorne; the key fit parameter is the radius of the inner edge of the black hole's accretion disk. Strong observational and theoretical evidence links the inner-disk radius to the radius of the innermost stable circular orbit, which is trivially related to the dimensionless spin parameter a_* of the black hole (|a_*| < 1). The ten spins that have so far been measured by this continuum-fitting method range widely from a_* \approx 0 to a_* > 0.95. The robustness of the method is demonstrated by the dozens or hundreds of independent and consistent measurements of spin that have been obtained for several black holes, and through careful consideration of many sources of systematic error. Among the results discussed is a dichotomy between the transient and persistent black holes; the latter have higher spins and larger masses. Also discussed is recently discovered evidence in the transient sources for a correlation between the power of ballistic jets and black hole spin.Comment: 30 pages. Accepted for publication in Space Science Reviews. Also to appear in hard cover in the Space Sciences Series of ISSI "The Physics of Accretion onto Black Holes" (Springer Publisher). Changes to Sections 5.2, 6.1 and 7.4. Section 7.4 responds to Russell et al. 2013 (MNRAS, 431, 405) who find no evidence for a correlation between the power of ballistic jets and black hole spi

The thermal ecology and population dynamics of grasshoppers in relation to grazing on a Breckland grass heath

SIGLEAvailable from British Library Document Supply Centre- DSC:DX173131 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

The ELAIS deep X-ray survey - I. Chandra source catalogue and first results

We present an analysis of two deep (75 ks) Chandra observations of the European Large Area Infrared Space Observatory (ISO) Survey (ELAIS) fields N1 and N2 as the first results from the ELAIS deep X-ray survey. This survey is being conducted in well-studied regions with extensive multiwavelength coverage. Here we present the Chandra source catalogues along with an analysis of source counts, hardness ratios and optical classifications. A total of 233 X-ray point sources are detected in addition to two soft extended sources, which are found to be associated with galaxy clusters. An overdensity of sources is found in N1 with 30 per cent more sources than N2, which we attribute to large-scale structure. A similar variance is seen between other deep Chandra surveys. The source count statistics reveal an increasing fraction of hard sources at fainter fluxes. The number of galaxy-like counterparts also increases dramatically towards fainter fluxes, consistent with the emergence of a large population of obscured sources

The ELAIS deep X-ray survey

We present initial follow-up results of the ELAIS Deep X-ray Survey which is being undertaken with the Chandra and XMM-Newton Observatories. 235 X-ray sources are detected in our two 75 ks ACIS-I observations in the well-studied ELAIS N1 and N2 areas. 90% of the X-ray sources are identified optically to R=26 with a median magnitude of R=24. We show that objects which are unresolved optically (i.e. quasars) follow a correlation between their optical and X-ray fluxes, whereas galaxies do not. We also find that the quasars with fainter optical counterparts have harder X-ray spectra, consistent with absorption at both wavebands. Initial spectroscopic follow-up has revealed a large fraction of high-luminosity Type 2 quasars. The prospects for studying the evolution of the host galaxies of X-ray selected Type 2 AGN are considered

ELAIS deep X-ray survey. I. (Manners+, 2003)

The ELAIS Deep X-ray Survey (EDXS) is being conducted in the northern ELAIS regions N1 and N2. The Chandra data consist of approximately 75 ks exposures in each field. Region N1 was observed on 2000 August 3-4 (OBSID 888) and N2 on 2000 August 2-3 (OBSID 887). The nominal aimpoints were: N1, 16:10:20.11 +54:33:22.3; and N2, 16:36:46.99 +41:01:33.7. The ACIS-I chips were used with the addition of ACIS-S2 and ACIS-S4. (3 data files)

The coincidence and angular clustering of Chandra and SCUBA sources

We explore the relationship between the hard X-ray and submillimetre populations using deep Chandra observations of a large, contiguous SCUBA survey. In agreement with other recent findings, we confirm that the direct overlap is small. Of the 17 submillimetre sources detected in this field at 850 mum, only one is coincident with a Chandra source. The resulting limits imply that the majority of SCUBA sources are not powered by acive galactic nuclei (AGN), unless the central engine is obscured by Compton-thick material with a low ( 1, even if they are purely starburst galaxies. Despite the low detection rate, we find evidence for strong angular clustering between the X-ray and submillimetre populations. The implication is that AGN and SCUBA sources trace the same large-scale structure but do not generally coincide. If bright submillimetre sources represent massive elliptical galaxies in formation, we suggest that (for a given galaxy) the major episode of star formation must be distinct from the period of observable quasar activity